Apparatus for lapping thin articles



Oct. 1, 1963 J. TORRES APPARATUS FOR LAPPING THIN ARTICLES Filed NOV. 3,1960 3 Sheets-Sheet l INVENTOR Jbsefvlz Torres,

ATTORNEYS Oct. 1, 1963 J. TORRES 3, 05,

APPARATUS FOR LAPPING THIN ARTICLES Filed Nov.- 3, 1960 5 Sheets-Sheet 2INVENT OR Jose v]; farms,

ATTORNEYS Oct. 1,119.63 J. TORRES 3 APPARATUS FOR LAPPING THIN ARTICLESFiled Nov. 3, 1960 3 Sheets-Sheet 3 INVENTOR W ATTORNEYS United States,Patent D 3,165,328 AP A RATUS FQR LAEPING THIN ARTICLES Joseph rorres,Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., acorporation of Pennsyivanra Filed Nov. 3, 1960, Ser. No. 67,081 8Claims. (Ci. 51-3) This invention relates to a lapping machine and moreparticularly relates to such a machine for lapping ultrathin metal partsperfectly parallel to a desired thickness.

In the splitting of very thin metal foils into very narrow strips, it isimperative that the slitting cutters be perfectly flat and parallel. Forexample, in the manufacture of precision instruments such as watches, itis often necessary to provide metallic strips cut from .000125 inchthick foil and having a width of .005 inch. Since the cutters should beno thicker than the width of the strip to be cut, it is necessary thatall the cutters be machined to an extremely close tolerance. Suchcutters are usually finished by lapping. However, up to the presenttime,

no lapping machine has been provided that can produce metal parts asfine as those now found necessary.

According to the present invention, it has now been found that by usinga novel lapping concept, wherein the articles to be lapped are movablymaintained between two relatively movable lapping plates, much betterresults can be achieved than was heretofore possible.

It is therefore a primary object of this invention to provide a machinefor lapping very thin metal parts.

It is also an object of this invention to provide a simple and compactlapping machine for lapping to very close tolerances.

It is also an object of this invention to provide a lapping machine inwhich the bottom lap moves relative to the top lap.

It is a further object of this invention to provide a lapping machinewherein the articles to be lapped are freely movable relative to boththe top and bottom laps.

It is another object of this invention to provide a lapping machinewherein the bottom lap moves relative to the top lap and wherein thearticles to be lapped are maintained for free movement between the topand bottom laps.

It is still a further object of this invention to provide a machine forproducing extremely thin parts.

These and further objects and advantages of the invention will becomemore apparent upon reference to the following specification and claimsand appended drawings wherein: I

'FIGURE 1 is a partial plan view of the lapping machine of the presentinvention;

FIGURE 2 is a vertical elevation partly in section taken along line 2-2of FIGURE 1; and

FIGURE 3 is a perspective view of the lapping machine of the presentinvention before it has been completely assembled.

Referring now to the several figures, a lapping machine, generallyindicated at 1, is mounted on a table 2. The table is provided withsuitable legs 4 which are attached in any desired fashion, such as byscrews 6. The table is provided with an annular opening 7 for a purposeto be later described.

An annular lapping machine casing '8 is mounted on the table 2 so thatit is coaxial with the hole 7. The casing 8 is preferably made with araised outer portion 18 and a flat base portion 12. A number of grooves14 are provided in the base portion 12. The base portion 12 is undercutat 16 to provide a lateral projection or ledge 18 which defines acentral opening 19. The casing is provided with an internal gear 20which can be made integrally with the casing, but is preferably made ofa Patented Oct. 1, 1963 ice softer material. As shown, the internal gear20 having gear teeth 22 is a bronze ring which may be mounted in thecasing 8 by force fitting or in any other suitable fashion. A pluralityof screws 24 are provided for securing the gear to the casing and forsecuring this assembly to the table 2.

A shaft 26 which can be driven by any suitable motor, not shown, extendsthrough the annular hole 7 in the table 2 and the opening 19 formed bythe projection 13 of the casing 8. A plate or spider 28 carrying acluster of planetary gears 30, 32 and 34 is fixedly mounted on the shaft26. The gears 39, 32 and 34 are freely rotatable in the plate 23. Forexample, as shown in FIGURE 2, the gear 32 is provided with a shaft 35that is journaled for rotation in an annulus 36 in the plate 28 by meansof any suitable bearing 38. As can be seen from FIGURE 1, the plate 28is eccentrically mounted on the shaft 26, the plate having four arms, inthree of which are mounted the gears 30, 32 and 34. The shaft 26 isattached at the other of these arms.

' A bottom lap plate 46 is provided with an internal gear 42 and anexternal gear 44 as is best seen in FIGURE 1. In the preferredembodiment, the external gear 44 is cut from the plate itself, which ispreferably of steel while the internal gear is a bronze ring 46 whichmay be attached to the plate by force fitting or by any other suitablemethod. The external gear 44 of this bottom lapping plate is designed toengage the teeth 22 of the gear 2% of the casing 8 while the internalgear 42 of the bottom lap plate engages the cluster of three planetarydriving gears 30, 32 and 34. The bottom lapping plate 49 is providedwith a turned recess 48 which is charged with a suitable lappingcompound. A plurality of concentric circular grooves 50 are formed inthis recess to keep the lapping compound from being worked to theoutside of the plate and out of the working area. The recess 48 is of adepth equal to the desired thickness of the finished parts.

A circular top lapping plate 52, preferably made of steel, is providedwith a number of concentric circular grooves 54. As in the case of thebottom lapping plate, the top lapping plate is charged with a suitablelapping compound and the grooves 54 prevent it from being worked to theoutside. The top of the plate 52 is provided with an annular groove 56which forms a handle 58. The handle 58 extends above the surface of theplate 52 and is provided with a diametric groove 60.

A U-shaped locking bar 62 of any suitable material has one leg 64pivotally mounted on a pin 66 carried by a bifurcated stud 68 which ismounted in any suitable manner on table 2. The other leg 70 of thelocking bar fits between a pair of pins 74 mounted on a stud 76 which ismounted on the table 2 in any suitable fashion. The bar 62 fits in thegroove 69 of the top lapping plate and secures it in position againstturning. It is to be understood that any suitable locking mechanism forthe top lapping plate could be used with equal facility and that theinvention is not limited to the embodiment shown.

In operation, the metal parts or cutters 78 to be lapped are placed inthe recess in the bottom lapping plate 40. As can be seen in FIGURE 3,the parts to be lapped keep each other from moving too freely and thevertical side Wall of the recess -48 keeps them from moving off the lap,yet still allows the parts to move and rotate against the bottom of therecess, giving a lapping action to the bottom of the parts.

The top lapping plate 52 is then placed in position. The diameter of thetop lapping plate is preferably such that it loosely fits in the lappingmachine casing 8. The top lapping plate is then secured in position bythe bar 62. The face of the top lapping plate rests on top of 3 thecutters and its weight provides the pressure for lapping.

When the motor is turned on, the shaft 26 rotates, causing the gearplate 28 to rotate. The cluster of planetary gears on the plate 28engage with the internal gear teeth 42 of the bottom lapping platecausing the bottom lapping plate to move eccentrically on the base 12 ofthe casing 3. The eccentric motion of the bottom lapping plate 4% causesa section of its external gear 44 to engage with the internal gear 22 ofthe casing. As

the bottom lap rotates under the weight of the fixed top lap, a lappingaction is given to the top part of the parts being lapped. As statedabove, the relative movement of the parts to be lapped with the chargedrecess in the plate 40 gives a lapping action to the bottom of the parts78. When the parts are lapped down to their desired thickness, nofurther lapping action will take place because the top lapping platewill rest on the bottom lapping plate, while the workpieces arecontained in the recess in the bottom lapping plate.

In a preferred embodiment of this machine, the pitch diameter of theinternal gear of the bottom lapping plate is 1 /2 inches; the pitchdiameter of the external gear of the bottom lapping plate is 5 inches;and the pitch diameter of the internal gear 22 of the casing 8 is 6inches. A satisfactory speed of rotation for the cluster of planetarygears has been found to be 43.8 r.p.m. Using this machine, a number ofcutters having a width of .005 inch can be made having perfectly fiatand parallel surfaces.

It will be apparent from the foregoing that the present inventionprovides a simple and compact machine for lapping parts far thinner thanhas been previously possible. In addition, the invention provides apractical way for producing a plurality of very thin parts, all beingperfectly parallel and having a uniform thickness.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a lapping machine having a casing, an input shaft, a spidereccentrically mounted on said input shaft, at least one planetary gearcarried by said spider, a lapping plate, said lapping plate having aninternal gear and an external gear, said internal gear meshing with saidplanetary gear, a section of said external gear meshing with a sectionof a gear provided on said casing.

2. In a lapping machine having a casing, drive means, gear meanseccentrically driven by said drive means, a

first annular lapping plate having an internal gear and an externalgear, said gear means meshing with said internal gear of said lappingplate and causing a section of said external gear to mesh with a sectionof an internal gear provided on said casing, and a second lapping plate,said second lapping plate being fixed relative to said casing wherebysaid first lapping plate moves eccentrically relative to said secondlapping plate.

3. A lapping machine comprising in combination, a casing, said casinghaving an annular internal gear, a drive shaft extending through saidcasing, a spider eccentrically mounted on said drive shaft, at least oneplanetary gear mounted on said spider, a first annular lappingplate,.said first lapping plate having an internal gear and an externalgear, said external gear having a diameter less than the diameter ofsaid annular gear, said planetary gear engag ing said internal gear andcausing said first lapping plate to move eccentrically, said eccentricmotion causing a section of said external gear to engage a section ofsaid annular gear, said first lapping plate supporting articles to belapped, and a second lapping plate, said second lapping plate beingsupported by said articles to be lapped and being restrained fromrotational movement.

4. The apparatus of claim 3 wherein said first lapping plate is providedwith a recess in which are supported said articles to be lapped.

5. The apparatus of claim 4 wherein said recess has a depth equal to thedesired thickness of said articles to be lapped.

6. The apparatus of claim 3 wherein said casing has an annular raisedportion having an inside diameter slightly larger than the diameter ofsaid second lapping plate.

7. The apparatus of claim 3 wherein said spider has four arms, one ofsaid arms being fixedly attached to said driving shaft, and the othersof said arms having planetary gears mounted therein.

8. In a lapping machine having a casing: said casing having a first gearmeans; second gear means; drive means for eccentrically driving saidsecond gear means; a first lapping plate having third and fourth gearmeans; said second gear means meshing with said third gear means andcausing a section of said fourth gear means to mesh with a section ofsaid first gear means; a second lapping plate; said second lapping platebeing fixed relative to said casing so that said first lapping platemoves eccentrically relative to said second lapping plate when saiddrive means drives said second gear means.

References Cited in the file of this patent UNITED STATES PATENTS1,937,459 Hill Nov. 28, 1933 2,178,937 Nieder et al. Nov. 7, 19392,469,5 6-3 Kinard May 10, 1949 FOREIGN PATENTS 881,572 France Apr. 29,1943

2. IN A LAPPING MACHINE HAVING A CASING, DRIVE MEANS, GEAR MEANSECCENTRICALLY DRIVEN BY SAID DRIVE MEANS, A FIRST ANNULAR LAPPING PLATEHAVING AN INTERNAL GEAR AND AN EXTERNAL GEAR, SAID GEAR MEANS MESHINGWITH SAID INTERNAL GEAR OF SAID LAPPING PLATE AND CAUSING A SECTION OFSAID EXTERNAL GEAR TO MESH WITH A SECTION OF AN INTERNAL GEAR PROVIDEDON SAID CASING , AND A SECOND LAPPING PLATE, SAID SECOND LAPPING PLATEBEING FIXED RELATIVE TO SAID CASING WHEREBY SAID FIRST LAPPING PLATEMOVES ECCENTRICALLY RELATIVE TO SAID SECOND LAPPING PLATE.